Apparatus for stretch-bending work in different directions under a predetermined tension



May 15, 1951 1.. s. HUBBERT 2,553,092

APPARATUS FOR STRETCH-SENDING w I IFFERENT DIRECTIONS UNDER A PREDETERM D NSION 5 Sheets-Sheet 1 Filed Nov. 21, 1945 VENTOR LES S. HUBBERT.

BY WQW ATTORN E S '5 Sheets-Sheet 2 INVENTOR HUBBERT s v RETCH-BENDING WORK IN DIFFERENT ATTORN EYS LESLIE S. HUBBERT.

BY T 9M; +T-M APPARATUS FOR ST DIRECTIONS UNDER A PREDETERMINED TENSION May 15, 195

Filed Nov. 21, 1945 May 15, 1951 L. s. HUBBERT 2,553,092

APPARATUS FOR STRETCH-BENDING WORK IN DIFFERENT DIRECTIONS UNDER A PREDETERMINED TENSION Filed Nov. 21, 1945 5 Sheets-Sheet 3 INVENTOR.

LESLIE S HUBBERT. WK y El so wmg'gww A TTORNE Y5 2,553,092 TCH-BENDING WORK IN DIFFERENT N 0 a N E T m m R T E T R E E m B R B P U A H m 5mm T L S m m WC E AR RI D P P A 1 5 9 l 5 1 Y m 5 Sheets-Sheet 4 Filed Nov. 21, 1945 INVENTOR LESLIE S. HUBBERT.

May 15, 1951 s H 2,553,092

UBBERT APPARATUS FOR STRETCH-BENDING WORK IN DIFFERENT Filed Nov. 21, 1945 DIRECTIONS UNDER A PREDETERMINED TENSION 5 Sheets-Sheet 5 INVENTOR.

ATTORNEYS JIE. .11

Patented May 15, 1951 2,553,092 I APPARATUS FOR STEETCH-BENDING WORK DIFFERENT DIRECTIONS UNDER A PREDETERMINED TENSION Leslie S. Hubbert, Mount Gilead, Ohio, assignor to H-P-M Development Corporation, Wilmington, Del., a corporation of Delaware Application November 21, 1945, Serial No. 630,090

2 Claims.

This invention pertains to an improved method and apparatus for metal stretching and bending.

It is a primary object of this invention to provide a metal stretching and bending press of ,.highly universal application for producing ccomplex metal shapes with precision and speed.

-Another object is to provide a metal stretchingand bending press capable of forming a work piece by bending in a plurality of different directions while automatically maintaining a desired tension in the work piece.

Still another object of this invention is'to provide a method of bending a work piece in a plurality of difierent directions. and controlling the tension in the work piece automatically during. said bending operation.

' A further, object is to provide a method of bending metallic work pieces by gripping the ends of the work piece and maintaining it automatically under a predetermined tension. while subjecting the intermediate portion of the work to bending forces acting in a plurality of different directions.

These and other objects and advantages will become more apparent upon reference to the accompanying drawings, in which:

Figure l is a side elevation of a metal stretching and bending press incorporating the features of this invention.

Figure 2 is a plan view of the press shown in Figure 1.

Figure 3 is a vertical transverse view on the line 33 of Figures 1, 2, and 4.

Figure 4 is an enlarged fragmentary plan view ,partly in section on the line 44 of Figure 1.

partly in section showing a modification of the transverse movement arrangement in Figure 2. Figure 8a is a section on the line 8c--8a of Figure 8.

. Figure 9 is an enlarged sectional view through a manual control valve for the hydraulic operating system.

Figure 10 is an enlarged sectional view through an automatic work tension control valve. Figure 11 is a diagram of the hydraulic operating and control circuit.

As an exemplary embodiment of this invention, there is illustrated a stretching and bending press comprising a frame l5 mounted on a suitable foundation IB. On each end of this frame is fixed the hydraulic tensioning motors or cylinders I! which control the movement of the work gripping jaws indicated generally at I8. Also mounted on this frame 15 is the main platen hydraulic motor or cylinder l9 upon which is mounted an auxiliary transversely movable platen or cross slide to which is fixed the die block 2|, Figure 3, and the work engaging die 22 so that this die may be moved vertically into the work intermediate the gripping jaws, and also moved transversely while in engagement with the work W by the hydraulic motor or cylinder 23 With a work piece W held in the gripping jaws I8, the application of fluid pressure tov the tensioning cylinder I1 is arranged to automatically maintain a predetermined tension in the workpiece as the die 22 is fed into it. Each of these cylinders I1 and their control mechanism is identical so that a description of one of them will suffice for both. Taking for example the tensioning cylinder I! on the left-hand side of the machine, there is provided a piston 24 operable in the cylinder l1 and having a piston rod 25 connected to it, Figure 11. The piston rod 25 is connected to a cross head 26, Figure 4, which isslidably mounted on suitable guide ways 21 formed on the frame l5 of the machine so that application of fluid pressure in the cylinders I! may control the horizontal reciprocation of the cross heads 26 on the. machine frame.

Pivotally mounted on suitable trunnion pins 28 and 28a in bearings 29 carried in the cross head 26 is the swivel block 30. On an extension 281) of the trunnion pin 28 is mounted a friction disc 3| and secured to the side of the cross head 26 is a friction plate 33 having a face 32 in engagement with the disc 3|. A spring 34 acts between the'washer 35 and the disc 3| to urge the latter against the friction plate 33. The washer is retained in place by a suitable cotter pin 33 and the entire assembly is operable frictionally to restrain tilting movement of the block 30. The disc 3| may include arm or bars M1: by which the block may be manually rocked in the bearings 29 to any desired posi tion to facilitate gripping the work.

For fine adjustment in setting the swivel block I 30 relative to the work to be gripped, there is also provided a hand wheel 31 having an integrally formed gear 38 journaled on a suitable shaft 39 mounted 9n the cross head 26. The

gear 38 in turn engages a larger gear 40 flxed to the trunnion shaft 28a so that upon rotation of the hand wheel 31, the swivel block 3% may be nicely adjusted to any desired position.

The work gripping jaw I8 is attached to an axially slidable sleeve member 6i through a pivot pin 42 which permits the jaw I8 to swivel about the axis of the pin :32 which is located normal to the axis Of the trunnions of the swivel block 3% but which pin extends radially outwardly and is confined in a slot %3 formed in the swivel block 30 so as to prevent rotation of the gripping jaw I8 and the sleeve 4: relative to the swivel block. The sleeve 4| has fixed to it a piston rod Al extending through a suitable packing 45 into a cylinder bore 46 in which operates a piston i! fixed to the piston rod 4d. Normally fluid pressure is maintained in the fluid pressure chamber 438 formed by the cylinder bore 46 and the piston 47 as shown in Figure 4 so that the pressure in I this chamber 43 will oppose the pull of the work on the work gripping jaws during the forming operation.

The work gripping device is arranged for gripping the end portions, in this instance, of an angle iron work piece W, and comprises an anvil block 49, Figures 5 and 6, which is engaged by the V of the angle iron W when a pair of clampi-ng wedges 56 are moved into clamping position by applying fluid pressure in the clamping cylinder chamber 5! behind the clamping piston 52 and the piston-rod 53 connected to the wedges 59. The work may be released from the work gripping jaws I8 by appropriately applyingfluid pressure in the chamber 5 1 behind the clamping piston 52.

As an alternate method of counter-balancing the jaws, the swivel block 3!! is provided with a counterweight arrangement comprising a cable 55, Figure '7, operating over a cylinder 56 formed integral with the gear 38 and upon the end of which is hu g a weight 51-, which may be varied in amount to suit the variation in the weight of the various different types of gripping jaws :l a and associated clamping wedges necessitated by different types of work pieces to be gripped in the machine. In this way, the machine is readily adapted for easy adjustment in presenting the gripping jaws in alignment with the work when initially placed in the machine so as to effect a rapid gripping and clamping of the work with a minimum of skill and eflort required on the part of the operator.

With the cross heads 26 moved to retracted position, a work piece or tangle iron W (which at this time is usually a straight linear member) is positioned in the machine, and the swivel blocks 38 rotated to proper aligned position by the hand wheels 3I or 31. The tensioning cylinders ii are then actuated by fluid pressure so as to move the gripping jaws I8 over the ends of the work to the position shown in Figure 5. A fluid pressure pump 58, Figure 11, receives a supply of fluid through a suction line 59 from the fluid reservoir 6B and transmits it through a pressure line BI connected to the clamping control valves 62 which may be manipulated to direct fluid pressure to the chambers =5I behind the clamping pistons 52, Figure 5. At the same time, these valves '62 connect fluid dischargedfrom the chambers 54 behind the clamping piston 52 to a drain line 63 for return of the discharge fluid to the reservoir 58. An appropriate .pressure gauge 58a connected through an appropriate line S-la to the pressure line 6| at all times indicates to the operator whether or not the work is properly gripped in the work gripping jaws during the forming operation. The work W is then ready for the compound bending operation which may be effected in this machine.

The die 22, Figure 3, carried on the die block 2I, has a notched portion 22a which engages the work piece W so that it may be moved upwardly to deflect the work in a vertical direction and may also be moved transversely in a horizontal direction to bend the work in still another transverse direction. The main platen cylinder I9, Figure 3, is fixed by appropriate screws 64 to the machine frame I5 and has operating therein a piston 65 attached to a piston rod 66 which projects upwardly through a suitable packing gland 61 and is connected by the screws 58 to the platen 69. This platen 69 is guided in vertical movement on suitable guide ways I formed in the frame I so as to adequately resist all transverse movements of the platen in the machine frame while at the same time providing freedom of vertical reciprocatory movement of the platen by the application of fluid pressure in the cylinder I9. On the platen 69 is mounted the auxiliar trans versely movable platen including the integral cylinder 23 in which is carried 'a piston II having integral piston rods Ill rigidly fixed'vat their outer ends by suitable nuts 13 to the lugs 69a of the platen 69 so that the application-of fluid pressure in the cylinder 23 on either side Of the piston 'I-I efiects relative movement of the auxiliary platen 26 along the transverse guide ways l4 formed on the platen 69.

After having gripped the ends of the work piece W in the gripping jaws I18 by appropriately manipulating the control valve 62, Figure 11, as described, the main platen actuating cylinder I9 is rendered operative to move the die 22 upwardly into the work W by appropriately manipulating a four-way control valve 15 'so that fluid pressure from the fluid pressure pump I6, which derives fluid through a suction line ='I'I from the reservoir BI] and transmits the fluid under pressure through a pressure supply line I8 connected to the valve 15, Figure 9. At this time, the valve plunger 15a is moved by positioning the control lever 15b in position I 50, connecting pressure line 78 to line "I9 so that fluid pressure is transmitted through the line 19 to the bottom chamber Bil in the cylinder I9. Discharge at this time from the upper chamber BI of the cylinder f9 into the line 82 is connected by the valve 15 to the drain line 83 for return of fluid to the reservoir In this way the piston moves upwardly to cause the die 22 to engage and bend the work in one direction, in vertical plane in this particular instance. When the lever 15b is moved to position 55d, the flow in lines 1-9 and 82 is reversed by connecting pressure from line it to line 82 while connecting line '19 to drain line 83 'to withdraw the die downwardly from the work. When the lever is in neutral or stop position 15b as shown in Figure 9, flow in lines "T9 and 82 is blocked off so as to arrest movement of the platen 627 in any desired position.

The die 22 maybe moved transversely or perpendicular to the vertical movement effected by the cylinder I9 by appropriately manipulating the four-way control valve 84, Figure 11, which is of similar design to the valve I5. The valve 84 is connected to the pressure line I8 and may atone time be operated to transmit fluid pressure through the line 85 to the chamber 23a and the transverse actuating cylinder 23 while connect- Ing its chamber 23b through the line 86 to the drain line 83 for transverse movement of the die in one direction. By manipulating the valve in the other direction, pressure may be applied through the line 86 to the chamber 23b while exhausted from the chamber 23a through the line 85 into the drain line 83 for transverse movement of the die 22 in the opposite direction.

' Itiis to be noted that the control valves I5 and 84 may be readily operated simultaneously or independentlyso as to effect the compound bending motions in a plurality of diiferent directions either simultaneously or independently so as to produce the most efiicient compound bending action in the work piece W.

. Both of the control valves 15 and 94 may be moved'to central or stop position so as to cut off -flow to or from their respective-cylinders I9 and 23 to arrest their motion in any desired position. After the bending operation has been completed, the transverse slide may be moved again to an appropriate initial starting position, such as shown in Figure 3, and stopped in that position by moving the control valve 84 into neutral so that the die 22 will have its slot'22a. in proper position to again engage a new work piece.

When the piston 65 reaches the end of its stroke, pressure builds up in the line 82 and is transmitted through a line 82a connected to the control mechanism 87 of the pump I6 to automatically shift it into neutral and unload fluid pressure from its driving mechanism in a conventional manner. There is also provided a control line 88 connected to the control mechanism 81' on the pump and responsive to excess pres-. sure in the line I8 which may develop during the forward or upward movement of the platen piston 65 or excessive resistance being encountered by the transverse movement of the auxiliary platen when actuated by the cylinder 23 so as to prevent damage to the pump and excess strain being develo fed in the machine mechanism. An appropriate gauge 89 connected through a line 78a to the line I8 gives the operator a direct indication of the forces being applied by both the vertical and transverse movements of the platen and auxiliary platen in forming the work to the desired compound bent condition.

As the work piece W is being operated upon by the vertical and transverse movement of the die 22, the tensioning cylinders I1 are so controlled as to automatically maintain a predetermined tension'in the work piece at all times while the compound bending operations are being performed on it. These cylinders I! are operated from a source of fluid pressure comprising the high volume, low pressure pump 99, Figure 11, which derives its source of fluid from the reservoir 60 through the suction line 9|, and a hi h pressure, low volume pump 92 which derives its source of fluid from the reservoir "69 through the suction line 93. Both of these pumps .99 and 92 are connected to discharge into the pressure line 94 which is connected to'the control valves 95, each connected to one of the tensioning cylinders I! through the lines 96 and 97. The valves 95 are four-way control valves of similar design to the valve shown in Figure 9, and positioned in a neutral or shut-off position so as to close ofi lines 96 and 9? when in neutral position to prevent. .fluid from escaping through the lines from the cylinder I7. With the work W held in the gripping jaws as described, and the die moved into the work to begin the bending operation, the pull on the gripping jaws by the work will tend to move 6. the pistons 24 toward the platen so as to develop pressure in the piston rod chamber 98 in the cylinder I'I. As this pressure develops, tending to resist movement of the piston rod 25 in the cross head towards the platen, pressure in the pressure chamber 48 behind the piston 97 in the cylinder 49 of the swivel block 30 also builds up and is transmitted out through the line 99 and through the check valve I and the line IGI whichgis connected to the tensioning control valve E92 shown in detail in Figure 10. The pressure thus developed in the line IBI moves the plunger I93 of this valve in opposition to the compression spring I9; so as to interconnect the line I05 connected to the cylinder chamber 98 with a line I99 which is connected to the other cylinder chamber Ill! behind the head end of the piston 24. Thus, as the tension in the work reaches a certain predetermined value, and which value may be readily adjusted by manipulating the hand wheel I98 and operating screw I09 of the valve I92, Figure 10, fluid will be allowed to escape from thechamber 98 through the valve I92 and the line I96 into the chamber IG'I so as to allow the piston 24 and cross heads 26 to yieldably ,move toward the platen during the forming operation. As the pistons 24 move toward the platen, fluid is drawn in through lines 97 and 91a and the check valves 97b from the reservoir 60 to keep the piston head chambers I07 properly filled with fluid; at all times. I The tension control chamber as in the swivel block 39 is kept properly charged with fluid at all times by pressure from a pump I I llwhich derives its source of fluid from the reservoir 60 through the suction line I II and transmits its pressure through the line I I2 which is. connected throughthe check valves I I3 to the line IIJI, and thence through a choke II4 to the line 99. The pressure developed by this pump I I9 isofja value below that required to shift the plunger I03 of the valve I92 against thepressure setting of the spring I0 3.v As pressure develops in the chamber IB during the bending operation, pressure -may readily pass through the checklvalve I99 from the line 99 to the line IIlI to actuate the plunger I03 while the check valve H3. closest'o prevent escape of this pressure (which is'greater than the pressure from the pump H9) from the line IIlI into the line II 2. Also, the check valve I I19 closes when pressure is suddenly released from the chamber 48 by the completion of the working stroke of the press and return of the platen while the choke permits a relatively slow small amount of fluid to pass from behind the plunger I03 of the valve I92 through the line H)! to the line 99 to retract the piston t! and fill the chamber 48 preparatory to gripping the next piece of work to be formed. This also stabilizes the operation of the valve plunger I93 to'p'revent its too rapidclosing and consequentjar to the machine if the pistons 24 of the cylinder I! were suddenly arrested in their forward tensioning movement. i

After the completion of the forming operation and the retraction of the platen and die the work is released from the gripping jaws and removed from the machine, the valves may be manipulated so as to now connect pressure from the line 94 to the piston rod chambers 93 of the cylinder I 1 while at the same time connecting the line 91 from the piston head chambers III! of these cylinders to the drain line 311; to thus cause the pistons 24 to retract and bring the "cross heads and workgrippingjaws back to iniarea-.092

tie-1 starting position. As the pistons approach the end of their retraction stroke, a port 'I'I5 in each of the cylinders I! is exposed by the passage of the piston beyond it to thus connect the fluid pressure in the chamber 88 through a *line II'E andv a check valve II! into the line 1-28 which is connected to the line 9'! to thus stop further movement of the piston 24 since the pressure now is connected under these conditions to the drain line 83 to the line 91 to thereby unload pressure from the pumps 95 and 92 while at the same time automatically stopping further retraction movement of the pistons 24 in the tensioning cylinders lI.

After having again placed a new piece of work to be bent in the machine and having adjusted the work gripping jaws by manipulating the hand wheels 31 to properly align them with the work to be gripped, the valves 95 are again manipulated to now connect pressure from the line 94 through the line 9'! to the piston head chamber Ill! of the cylinder II while connecting the chamber 98 through the line 96 to the drain line 83 so as to in this way move the cross heads toward the platen to initially position the work gripping jaws with the work. A suitable pressure gauge I !9, connected to the line 94 through the line 94a, serves to indicate the operating condition in the pressure circuit served by pumps 90 and 92. A pressure gauge I connected through a line Ifila indicates to the operator the behaviour of the tensioning pressure in the chambers 48 of the cylinders 46 in the swivel blocks 30 to assist in determining the proper manipulation of the platen and auxiliary transversely movable platen to eifect the most satisfactory bending and forming operation .on the work.

There has thus been provided a metal stretching machine in which a Work piece W is gripped at each end and held at a predetermined tension as pressure is exerted intermediate its ends to deflect it in one direction and wherein force is exerted in a perpendicular direction to this last mentioned force at the same time so as to bend the work piece into a two-dimensional position while at all times maintaining a predetermined tension in the ends of the work piece during the forming operation.

Figure 8 shows a modification in which the transverse relative movement of the work and main platen is provided by mounting the work gripping jaws I8 carried in the swivel blocks 30 on cross slides I2I carried on suitable guide ways I22 formed on the cross head 26a. Appropriate hydraulic actuating motors or cylinders I23 are fixed on the cross heads 26a and have pistons I24 and piston rods I25 connected by suitable means I26 to the cross slides -I2I so that application of fluid pressure in said cylinder I23 may be utilized to transversely reciprocate the slides and therefore the work gripping jaws I8. In this arrangement-the die block 2| and die 22- are rigidly fixed to the platen 69, there being no transversely movable auxiliary platen Zll required. IIhe die is reciprocated in vertical movement [by the piston IS.

.The hydraulic actuating and control arrangement utilized in connection with this modification is shown in broken section line in Figure 11. In this arrangement, of course, the control valve 84,, the associated lines 85 and .86, and the transverse auxiliary platen actuating cylinder 23 would be dispensed with, Each of the cross slide actuating cylinders I23 is provided with a control valve I21, of similar design to the valve shown in Figure 9, which receives a pressure su ly through the lines 18a and isconnected through drain lines 83a to the drain line 83. The pressure chambers in the cylinders I23 on each side of the pistons I24 are connected through suitable lines I28 and I29 with the valves I21 which are four-way control valves movable to a neutral position to trap the fluid in'the cylinders I23so as to hold the cross slides in any selected position during the movement of the platen and die 22. These valves I2] may be manipulated to efiect any degree of cross slide movement in either direction for the cross slides I2I.

In this modification, the end portions of the work may be moved transversely to any degree relative to the die 22 so that the end portions may each be bent to different degrees while theplaten may be raised into the work to effect still other configurations of bending in the work. Thus this stretching and bending apparatus is adapted to bending work in aplurality of different directions to effect a multiplicity of bending operations on a work piece with a single gripping of the work piece in the machine and accomplishing these operations ,while at all times maintaining a predetermined tension in the work piece.

While the apparatus herein disclosed and described constitutes a preferred form of the invention, it is to be understood that the apparatus is capable of mechanical alteration without departing from the spirit of the invention and that such mechanical arrangements and commercial adaptations as fall within the scope of the claims are intended to be included herein.

Having thus fully set forth and described this invention, what is claimed as new and desired to be secured by United states Letters Patent is:

1. In a stretch-bending press; the combination of a frame; a pair of work-gripping members carried in longitudinally spaced order on said frame and mounted for limited longitudinal sliding movement on said frame; fluid-pressureresponsive means connected with each of said work-gripping members for controlling the movement thereof with respect to said frame; a pressing head carried in said frame betweensaid gripping members for engagement with an intermediate portion of a workpiece carried between said gripping members, said pressing head being mounted in said frame for movement in a plurality of angularly related planes; fluid-pressureresponsive means for moving said pressing head in each of said angularly related planes; and valve means connected with the fluid-pressureresponsive means associated with said workgripping members and operable in response to bendin forces applied to a workpiece carried between said gripping members by engagement with said pressing head to relieve fluid pressures Within said first-named fiuid-pressure-responsive means and thereby permit said gripping members to move inwardly of said frame and toward one another.

2. In a stretch-bending press; a frame; a pair of relatively spaced workpiece-gripping members carried longitudinally of said frame for limited sliding movement along the longitudinal axis of said frame; fluid-actuated means connected with each of said workpie er pp ng members and operable to impart limited sliding movement to the latter; a pressing head carried in said frame for movement in a plurality of angularly related planes, said pressin head being engageable with a workpiececarried between said gripping mem bers; a plurality of fluid-pressure-responsive means connected with said pressing head for moving the latter in said plurality of angularly related planes; and means connected with said fluid-actuated means and responsive to a predetermined bending stress within a workpiece carried between said gripping members to relieve fluid pressures within said fluid-actuated means to thereby maintain a constant tension within a workpiece carried between said gripping members throughout bending operations.

LESLIE S. HUBBERT.

REFERENCES CITED The following references are of record in the file of this patent:

Number 10 UNITED STATES PATENTS Name Date Kellogg Apr. 23, 1929 Kellogg Apr. 23, 1929 Bruno Apr. 18, 1939 McMillin et a1 July 14, 1942 Amiot Aug. 11, 1942 McMillin et a1 Sept. 1, 1942 McMillin et a1 Sept. 1, 1942 Lermont et a1 Nov. 17, 1942 Urschel May 4, 1943 Lermont et al Aug. 10, 1943 Summers Feb. 22, 1944 Flowers Apr. 11, 1944 Seifried Aug. 29, 1944 Hawkes Nov. 18, 1947 Greene Mar. 2, 1948 Hochreiter July 27, 1948 

